Manufacture of lubricating oil



Patented June l, res,

I ACTURE F LUBRICA'EENG UH;

Francis X. Govers, Vincennes, Ind., assignor to' llndian Refining Company, lbawrenceville, Ml

a corporation of Maine No Drawing. Application March 29, 1933, a Serial No. 663,341

3 Claims. (Cl. 1196-17) This invention relates to the manufacture of mineral lubricating oils and more particularly to the manufacture of high viscosity index, low pour test lubricating oil from wax bearing mineral oils.

In its broadest aspect, the invention contemplates an' improved process of treating hydrocarbon oils, particularly paraifin-bearing lubricat-. ing fractions of petroleum with solvents to selectively produce therefrom low pour test lubricating oils characterized by having a desired viscosity temperature relationship and improved lubricating qualities. The invention contemplates a process of manufacturing lubricating oils having low pour and cloud tests, low sulphur content, low Conradson carbon content, relatively high viscosity index and freedom from bodies of little or no lubricating value. p

Lubricating oils, as ordinarily made from naphtheme-base crudes, have low pour and cloud tests,

low Conrad'son carbon content, but have low vis cosity indices and fairly high sulphur content. On the other hand, lubricating oils, as ordinarily made from paraffin-base erudes of the Pennsylvania type, have high pour and cloud tests, high Conradson carbon content and fairly high sulphur content, depending on the source of particular crude used. Oils derived from mixed base crudes fall somewhere between these limits al- 39 though usually high in sulphur content. Oilsof the Pennsylvania type, as well as those derived from mixed base crude sources, are difiicult to refine without undue loss and impairment of their lubricative value. In all cases, it is difiicult, by methods now employed, to reduce the sulphur content of these lubricating oil fractions to a desired point, regardless oftheir source of crude.

I have discovered that by the use of the methods herein disclosed lubricating oils of any desired viscosity index'and scale of purification coupled with low pour test and low cloud test, can be made from mixed-base or paraflin-base crudes and the oils so produced are characterized further by low Conradson carbon and low sulphur content. The

45 obtaining of oils having these desiredqualities does not depend on methods involving redistillation or acid treatment, although such redistillation or acid treatment can be coupled with the methods herein disclosed if so desired.

Lubricating oils of high viscosity index are characterized by having a relatively narrow increase in viscosity with respect to temperature. Such oils have the property of possessing the desired viscosity at elevated temperature with not toogreat a loss of mobility at very low temperature. The viscosity index of a given oil is readily determined by resorting to the method of Dean and Davis, published on pages 618-619 of the 1929 issue of Chemical and Metallurgical Engineering.

More specifically the invention comprises mixing with a wax-bearing fraction of a mineral oil a solvent mixture composed of aniline and a modifying solvent selected from the group comprising isopropyl ether, ethyl ether, benzol, toluol, and 10 the like, in such proportion to each other and to the oil that the mixture has substantially complete solvent action on the oil at temperatures of around 100 F., and-at temperatures of around 0 F. substantially complete solvent action on the 15 liquid hydrocarbons therein but substantially no solvent action on the solid hydrocarbons therein and of such a nature that upon cooling a solution of the mineral oil fraction in such solvent mixture to 0 F. and removingthe solid hydrocarbons 20 so precipitated and the solvent liquid the resulting oil has a cold test of substantially 0 F. or below.

The mixture is then chilled to form a precipitate of solid or semi-solid material comprising 25 suspended wax or solid hydrocarbons which are insoluble in, and immiscible with, the desired solvent mixture. The mother liquor is separated from the chilled mixture, advantageously by filtration. The separated mass of solid hydrocarlocus is then washed free of mother liquor containing dissolved oil by additional quantities of chilled solvent liquid of approximately the same composition as used in the original mix.

A portion of the first part of this wash filtrate may be added to the original filtrate. The extent of such addition depending on the amount or percentage of oil contained in such wash filtrate.

From the original filtrate or mixture of original filtrate and wash filtrate is then evaporated one of the component solvents in an amount sufficent to effect the desired alteration in the selective solvent action of the mixture. If desired this resulting mixture may be treated with additional amounts of the remaining solvent component.

This resulting mixture of altered composition may be cooled or chilled to still further afiect its solvent action and is allowed to stand and effect.

.a sharp separation into two layers. The-upper layer contains oils characterized by relatively highviscosity index and the lower layer contains oils of relatively low viscosity index.

The amount and character of the separation is influenced by the amount of alteration in the,

percentage composition of the component parts comprising the solvent mix and the temperature to which such altered composition mixture is chilled. If desired the modifying solvent may be removed in successive stages, subjecting the remaining mixture of dissolved oil and solvent to cooling in' each instance to thereby successively separate fractions of difiering characteristics as may be desired.

It is contemplated that the wax-bearing fraction may be subjected to preliminary refining either with acid or by extraction with a suitable solvent such as the selective solvent component of the mixture used in the subsequent steps. The

resulting treated fraction is then dewaxed by modifying solvent. The solvent component of relatively high selectivity may be aniline, or a solvent of like solvent nature and the modifying solvent of relatively less selectivity may be isopropyl ether, ethyl ether, toluol, benzol, or a solvent of like solvent nature.

As an example of the process;

An acid treated wax distillate having the following approximate characteristics, gravity 26 B., viscosity of '70 Saybolt universal seconds at 210 F., and a pour test of F. is well mixed with isopropyl ether. Following this, aniline is then added. The proportions of these two solvents used comprises about 60 parts of ether to about'40 parts of aniline. The mixture is well stirred, chilled to 20 F., and while maintained in this chilled condition, introduced'to a pressure type filter such as described in my copending application, Serial No. 585,844, wherein the solid hydrocarbons are separated to produce a filtrate substantially free from dissolved wax and solid hydrocarbons. The filter cake, without removal from the filter, is washed with additional solvent liquid mixture of substantially the same composition and which has been chilled to a temperature of -20 F. This wash filtrate is used for part of the solvent mixture in a succeeding batch, allowance being made for the oil contained therein.

The wax slurry is drawn off from the filter and the solvent removed by evaporation or distillation in a reducing or non-oxidizing atmosphere, such as carbon dioxide for example. The wax, free from solvent, is then steam treated in the presence of clay and contact filtered. The resulting wax is practically water white and will have a melting point of approximately 138 F.

From the dewaxed filtrate a portion, or substantially all, of the isopropyl ether isevaporated,

dependingupon the degree of separation desired.

The resulting mixture may be chilled to any temperature desired, upon which separation into two layers will occur. One layer will comprise the high viscosity index constituents, while the other .layer will contain the low viscosity index constituents.

In the event that substantially all of the isopropyl ether isevaporated from the dewaxed filtrate,'it may be advantageous to extract the resulting mixture with an additional quantity of aniline. This extraction may be carried out by countercurrent methods at a temperature of around 60 F., for example, using about one part of aniline to two parts of oil. As a result of this extraction, the oil will, upon settling, be separated a Conradson carbon content not greater than 0.02% and a sulphur content not greater than 0.09%.

The invention is not limited to the production of final products of the characteristics of those produced in the examples given above. Products of varying characteristics maybe produced by varying the proportions of solvent liquids and their concentration and the temperature at which the treating steps are carried out.

Furthermore, the invention is not limited to the treatment of .wax distillatesuch as given in the examples herein but is adapted to the treatment of other parafiin-containing fractions, precipitates or materials somewhat similar in nature derived in various ways from mineral oils.

Thus my invention is applicable to the treatment of hydrogenation products resulting from the hydrogenation of carbonaceous materials, or mineral oils including liquid or solid hydrocarbon fractions derived from mineral oils. Hydrogenation products may contain substantial quantities of waxy or paraffin material as well as other constituents of relatively low lubricating value. By treating such products in accordance with my invention, final products of desired characteristics can be obtained.

The invention is not restricted to any particular operating condition such as that of temperature, or the composition of the solvent mixtures employed since these conditions may advantageously be varied, depending upon the nature of the fraction undergoing treatment as well as upon the particular characteristics desired in the final product.

It is also contemplated, in many instances, that it may be of advantage to carry on the filtration step in the presence of a com'minuted solid filteraid material. Such material may be admixed with the chilled mixture ofoil and solvent liquid prior to introduction to the filtering means.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may

.be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim: I

1. The process of manufacturing viscous lubricating oil having a pour test of 0 F. and below and a viscosity index of and above from viscous wax-bearing mineral oil comprising mixing with the oil a solvent consisting of about 40% aniline and 60% isopropyl ether in proportion with the oil such that at 0 F. and below the mixture has substantially complete solvent ac-.

the mixture .to a temperature of 0 F. and below to precipitate the wax,vremoving the precipitated wax, vaporizing a large portion of the isopropyl ether from the dewaxed-mixture, extracting the remaining mixture with aniline, a portionof which comprises aniline used in the dewaxing;

step, separating the mixture while at a temperature of around 60 F. into extract and raflinate phases, removing the railinate phase, and remov ing the solvent from said ramnate phase to produce oil having the aforesaid characteristics;

2. The process of dewaxing viscous wax-bearing oil to produce oil having a pour test of 0- F.

and below' which comprises mixing the oil with a. solvent consisting 01' about 40% aniline and action on the solid hydrocarbons, and such that.

upon cooling the mixture of solvent and oil to 0 F. and removing the solid hydrocarbons precipitated and the solvent liquid, the resulting oil' has a cold test of around 0 F., chilling the mixture to a temperature of 0; F. and below to precipitate the wax, and removing the precipitated wax therefrom.

8. The process of manuracturing high viscosity index lubricating oil having a low pour test from wax-bearing mineral-oil which comprises mixing with the oil a, solvent liquid mixture .com-

posed of aniline and a modifying solvent, such as isopropylether, having substantially no selective action as between constituents of the oil of dlfiering viscosity ln'dices and mixed with each other and with the oil in proportions such'that at temperatures ofaround 0 F. the mixture has substantially complete solvent action on the oil, and substantially no solvent action on the wax. chilling the mixture to precipitate-wax constituents of the oil, removingvthe wax thus precipitated, removing from the resulting dewaxed mixture a suitable portion of the modifying solvent to thereby render the remaining solvent liquidselective as between constituents of the oil of 2 FRANCIS x; GOVERS. 2' 

